Poison hemlock is a toxic plant that has appeared in history and literature for thousands of years. But what is it, exactly? And why is still a problem today? We are going to dive into the botanical world of plant identification and toxicology with a short Q & A about this impressive plant.
What is poison hemlock?
Poison hemlock (Conium maculatum) is a biennial plant that can grow along streams, ditches and edges of cultivated fields throughout Illinois. It has a hollow and distinct purple-spotted stem, with fern-like leaves, reaching a height of 10 feet. The plant has one white root that is often mistaken for a parsnip or carrot. This similarity has been the cause of many poisonings. Poison hemlock also produces white flowers that are often mistaken for Queen Anne’s lace, another flowering plant.
Figure 1. (above, left) Poison hemlock flowers. Figure 2. (above, right) The unique lower stem of a poison hemlock plant, mottled with purple spots.
Figure 3. (above) Queen Anne’s lace (Daucus carota), also known as wild carrot, is often confused with poison hemlock due to the similarity in blooms.
What should you do about a poison hemlock exposure?
For all known or suspected exposure to poison hemlock, call the Illinois Poison Center (IPC) at 1-800-222-1222. Do not wait for symptoms to occur before calling the IPC. One of our poison specialists will give instructions for symptom observation and possible referral to a healthcare facility for immediate medical attention.
Which famous philosopher died from poison hemlock ingestion?
If you guessed Socrates, you are correct! In 399 BC, the ancient Greek philosopher was sentenced to death by drinking hemlock extract.
The Death of Socrates (1787), by Jacques-Louis David
What is causing the recent spread of poison hemlock?
According to recent reports in our sister state, Indiana, there has been an increase in the spread of hemlock in the region due to a combination of weather and agricultural farming. Causes include modifications in farming practices, the choice of herbicide used or an introduction of a species not previously encountered, according to Aaron Hager, Associate Professor of the Department of Crop Sciences at the University of Illinois. The combination of these factors is favorable for poison hemlock spread and makes it more difficult to control.
What are the signs and symptoms of hemlock poisoning?
Poison hemlock contains coniine, a toxic chemical similar to nicotine. A common cause of hemlock poisoning is skin contact, since any part of the plant can cause toxicity and potential rash. Poisonings commonly occur when poison hemlock is eaten after being mistaken for wild carrots or wild parsnips. Symptoms of ingestion may include nausea, vomiting and confusion. More serious cases have involved muscle paralysis, decreased breathing and even death.
What’s the difference between poison hemlock and water hemlock?
Water hemlock (Cicuta douglasii), sometimes referred to as spotted cowbane, looks very similar to poison hemlock but tends to prefer moister environments closer to rivers and marshes. There is also a difference in the plants’ toxins: Water hemlock contains cicutoxin, which causes delayed neurological symptoms and prolonged seizures that are hard to treat. Its stems are about four feet shorter than poison hemlock. Water hemlock grows in nearly every state in the United States and two-thirds of Illinois counties. Both of these plants are mistaken for wild carrots and parsnips.
Figure 4. (above) Water hemlock
How can you dispose of poison hemlock safely?
The Department of Agriculture recommends using both mechanical and chemical strategies for the best results in poison hemlock control. The goals is to prevent seed production and seed movement from mature plants, which will help prevent the spread of the toxic herb. Effective methods include physically removing the plant, applying an herbicide and mowing before it has a chance to seed. Do not burn poison hemlock, as the inhaled smoke can be an irritant.
Do you have any questions about poison hemlock or the topic of today’s blog? Email us at IPCadmin@team-iha.org.
Concerned about an exposure to a potentially harmful substance? Call the Illinois Poison Center at 1-800-222-1222 or visit us at the Illinois Poison Center.
–Shin Allison, PharmD candidate and Tony Burda, Rph, CSPI, DABAT
